Edge Thickness before HT

J

JamesPEmmons

Joined
Sep 3, 2008
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269
Working with O1 steel, normally I try to keep the edge thickness around 0.050" before heat treat. On the knife I am currently working on I had to take it down to 0.020" to get the flat grind to clean up.

My question is this safe or will I end up with cracks in the edge? If this is safe what is the thinest I make the edge before HT?

I HT with a digitally controller gas forge and quench in Canola oil (until I get some really quenching oil) heated to 130 after a 10 minute soak at 1525. Then temper three cycles (thinking about reducing this to two cycles) at 425 for 1.5 hours. I have been get good result so far.

Thanks,

James
 
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I routinely leave my edges around 0.03 prior to heat treating on hunter size knives. I've done that with O-1, CPM154, 1095, 440C, and ATS35. As long as your grinding is done evenly, you normalize prior to hardening, and you go in the quench straight or get it between the plates evenly, things most of the time work out. If it warps and you don't correct it before it sets up, stress relieve at 1200 for about 45 minutes, straighten it while it's hot, normalize, and re-heat treat.

If you're really worried about warping, run the cutting edge over the wheel parallel with the belt a few passes. You'll be surprised at how little you have to remove to get back to that 0.03 + range. If you're worried about the ricasso being lower than the edge, take that down a pass or two as well.

--nathan
 
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